Tech Talk #4 – Listen To Your Engine

By David Reher, Reher-Morrison Racing Engines

“A race car deserves the same respect as an airplane”

Racing engines are like dogs and babies: They communicate in ways that not everyone can understand. When Duke, my Labrador retriever, is thirsty or wants to go outside, he doesn’t need to send me a memo or speak to me in perfect English. We communicate in nonverbal ways, and he has trained me how to interpret his actions and expressions. I have also learned that if I ignore what Duke is telling me, it’s very likely that I’ll end up with a mess on the kitchen floor to clean up.

A racing engine will also tell you when it is in distress. There are early warning signs that indicate when something is wrong. If you learn how to listen to your engine and interpret its messages, you can save a ton of money. And if you chose to ignore what your engine is saying, you will probably end up with a mess in the bottom of the oil pan to clean up.

Like electricity, racers follow the path of least resistance. If an engine suddenly spits out a pushrod, a typical reaction is to decide that the part was defective. You replace the pushrod and make another run – and the engine usually breaks a lifter, drops a valve, and pulverizes the piston, block, and cylinder head. Instead of taking a few minutes to investigate the reason for the original failure, you’re now facing days of work and a big repair bill.

Many of our engine customers make over 600 runs in a season without a single mechanical problem. Are they just lucky? Perhaps – but they make their own luck by being observant and conscientious. They don’t take their engines for granted. They check the valve lash regularly, look for broken springs routinely, and inspect the oil filter religiously. They don’t count on good fortune to keep their engines running in top form.

My number one rule of prevention is to never ignore a significant change in valve lash. If one valve suddenly has 20 thousandths more lash than the other valves, find out why. Is the valve bent, is the lifter broken, is the pushrod tip burned up? Random failures are rare; things usually happen in a racing engine for a reason.

When you change your engine’s oil, don’t just chuck the filter into the recycling bin. Cut open the canister and take a close look at the filter element. (We sell a tool that opens an oil filter like a can opener. It’s such a neat deal that we now include it in our “Engine Care Kit.”) Are there chunks of metal in the filter? A little aluminum glitter is nothing to be concerned about, but if there are bits of copper or pieces of magnetic metal, you need to find the source. You might have a bearing that’s going bad or a camshaft sprocket that is galling the front of the block. You can ignore the problem, but it’s not going to go away.

If you are using an automatic transmission, I recommend that you always check the crankshaft thrust clearance after installing a torque converter. I’ve seen a lot of unnecessary engine damage caused by mismatched converters and motor plates. It’s easy to wedge a converter between the engine and transmission if the motor plate is the wrong thickness – a situation that is just about guaranteed to kill both the engine’s rear main bearing and the transmission’s front pump.

When I was studying for my pilot’s license, my instructors hammered on the point that an airplane should only be operated within certain parameters. If the engine isn’t running within the specified range, you don’t take off . . . period. When a Cessna loses oil pressure at 10,000 feet, you can’t just pull over to the side of the road and wait for the Auto Club to arrive. A race car deserves the same level of respect.

When an engine begins to run outside of its normal pattern, something is usually wrong. A sudden change in oil pressure or water temperature definitely warrants further investigation. It may be something as simple as a defective gauge or an electric water pump motor that’s gone bad – or it could be something major. I always use a section of old-fashioned rubber radiator hose on our Pro Stock’s cooling system so I can squeeze the hose and feel the water flowing. Hard lines may be pretty, but in a noisy racing environment you can’t be sure that an electric water pump is working properly unless you can see and feel the water circulating.

The most reliable barometer of a race car’s overall condition is its on-track performance. Drag racing cars have become so consistent that elapsed times are within hundredths or thousandths on every run. By monitoring and correcting for weather conditions, you can accurately predict your car’s performance. If the actual numbers differ significantly from what the instrumentation tells you they should be, that’s a signal that something is amiss. The trouble may not be in the engine; it could be a transmission problem, a malfunctioning converter, a dragging brake caliper, or a rearend going bad. Your time slip is an excellent diagnostic tool for the entire vehicle.